Pouring trough for centrifugal casting machine



Nov. 15, 1966 s. GURAK 3,284,860

POURING TROUGH FOR CENTRIFUGAL CASTING MACHINE Filed Jan. 29, 1964United States Patent M 3,284,860 POURING TROUGH FOR CENTRIFUGAL CASTINGMACHINE Stanley Gurak, Birmingham, Ala., assignor to United States Pipeand Foundry Company, Birmingham, Ala., a corporation of New Jersey FiledJan. 29, 1964, Ser. No. 341,056 2 Claims. (Cl. 22-65) The presentinvention relates to pouring troughs for use with centrifugal castingmachines.

In the manufacture of cast iron pipe the pipe is centrifugally cast in asubstantially horizontal mold which is rotated about its longitudinalaxis. The molten metal is delivered to the inside of the mold by meansof a pouring trough which extends for substantially the full length ofthe mold, and the metal is distributed along the length of the rotatingmold as it discharges from the end of the trough by relativelongitudinal movement between the mold and trough.

When molten metal is poured in the trough, the inside of the troughattains a much higher temperature than the outside of the trough. Alsothe bottom portion of the trough which conveys the iron attains a muchhigher temperature than the top portion of the trough. This unevenheating of the trough causes it to warp and bow with the result that itcannot be maintained in proper alignment with the mold and the moltenmetal does not flow down the trough in the proper manner.

To overcome the difliculties inherent in the unequal expansion due tothe temperature gradient between the inside and outside surfaces of thetrough and the bottom portion and the top portion it has been thepractice to use a continuous outer steel shell lined with longitudinallyshort segments of a more refractory material. When these segments areproperly mounted in the trough they prevent excessive warping and bowingof the trough. Maintenance costs on such troughs are high, they do notpresent a continuous smooth surface for the metal to flow down, and theyare not suitable for use in operations wherein the trough is overturnedafter each pipe is cast in order to dump out the iron splinter left inthe trough.

In recent years the use of single-piece troughs has increased. However,despite the use of special cross-sectional designs and support means thewarpage and bowing of the trough is still a major problem which has notheretofore been satisfactorily eliminated from the cast ing operation.

The invention has for its object the provision of an improved troughwhich does not distort due to heat, which presents a continuousuninterrupted surface down which the molted metal flows and which may beoverturned to dump out iron splinters.

Other objects of the invention will be apparent from the description anddrawings.

In the drawings:

FIGURE 1 is a side elevation view of the trough of the presentinvention.

FIGURE 2 is a top elevation view of the trough of FIGURE 1.

FIGURE 3 is a transverse section of the trough of FIGURES 1 and 2.

The trough of the invention illustrated in FIGURES 1-3 is suitable foruse in any retractive casting operation wherein a pouring trough isused. Such troughs are supported at one end in cantilever fashion andthis supported end is mounted adjacent the pouring ladle of a castingmachine so that molten metal may be poured from the ladle into thetrough. The opposite end of the trough is unsupported and is arranged toenter and traverse a spinning mold when there is relative longitudinalmovement between the trough and mold so that Patented Nov. 15, 1966molten metal pouring from the unsupported end of the trough isdistributed along the length of the mold. The relative longitudinalmovement between the trough and mold may be accomplished by mounting themold so that it may be moved longitudinally and/ or by mounting thetrough and pouring ladle so that they may be moved along thelongitudinal axis of the mold. Since the instant invention relatessolely to the construction of the pouring trough and the details of thecasting method and apparatus set forth above are well known, the castingmachine is not illustrated. It is suflicient to point out that thesupported end 3 of the illustrated trough is mounted in cantileverfashion on a support 7 which is adjacent the pouring ladle of a castingmachine, and that unsupported end 5 of the illustrated trough is mountedso that it may enter and traverse a spinning mold when there is relativelongitudinal movement between them.

The trough of the present invention, as illustrated in FIGURES 1-3,comprises an inner channel 1 mounted in a support channel 2. These twochannels are secured togethed adjacent the support end 3 of the troughby means of tack welds 4. The discharge end 5 of the inner channel 1extends beyond the support channel 2 for a short distance and isappropriately shaped to give the desired angle of impingement of moltenmetal pouring from the trough onto the surface of a spinning mold.

Referring specifically to FIGURE 3, the innerchannel is seen to have asubstantially circular outer surface and an inner surface defined by asubstantially semicircular bottom and two slightly divergent sidesextending upwardly tangentially, from the curved bottom. The outersurface of the inner channel being greater than a semicircle, the Widthof the inner channel at the top is less than its width at the horizontaldiameter. The support channel is defined by an inner circular surface ofsubstantially the same diameter as the outer surface of the innerchannel and an outerco-axial circular surface. The support channelencircles the inner channel, and since both its inner and outer surfacesare greater than a semicircle, the opening at the top of the supportchannel is less than either the diameter of its inside surface or thediameter of the outside surface of the inner channel. Thus the innerchannel cannot be removed from the support channel through itslongitudinal opening or mouth. This permits the trough to be turned overto dump the iron splinter which remains after every casting cycle, therebeing no danger whatsoever that the inner trough will be dumped from thesupport trough.

The clearance between the inner and support channels is such as topermit free longitudinal expansion of the inner channel within thesupport channel but is small enough to prevent any appreciable verticalor transverse movement of the inner channel within the support channel.In other words, the inner channel is securely held against any movementexcept longitudinal expansion, and as a result it will remain asstraight as the support channel. Since the support channel does not comein contact with the molten metal it will not be subject to anyappreciable extent to the thermal expansion forces which will tend tobow and warp the inner channel.

Preferably an air space 6 is provided between the bottom of the innerchannel and the inside opposite surface of the support channel. Sincethe bottom of the inner channel is subject to the greatest concentrationof heat and since there is not any balancing expanding mass at the endof the diameter opposite the bottom of the channel, the open top, thereis a great tendency for it to bow in the vertical plane. The air space 6is provided to limit the heating up of the bottom section of thesupporting channel. This reduces the expansion forces which would tendto cause the support channel to bow in the vertical plane and make itineffective in preventing bowing of the inner channel. On the otherhand, heat transfer to the side sections of both the inner channel andthe supporting channel will be substantially equal so that there will bea balancing force on each side of the trough axis which counteracts thebowing tendency in the horizontal plane caused by the expansion of theopposite side of the trough. If it is desired to provide the trough withspray equipment a spray nozzle mounted adjacent the discharge end of thetrough can be fed by means of lines positioned in the cavity formed byair space 6.

The preferred method of manufacturing the trough of the presentinvention is to slide one tube which is to be the inner channel into asecond tube which is to be the support channel. The resulting concentrictube construction then serves as a blank from which the trough ismanufactured. The trough is formed by milling a longitudinal sectionfrom the blank to provide the desired inside configuration. This permitsthe use of standard steel tubing which requires little, if any,machining to form the starting blank, and the final trough configurationcan be accomplished by a simple machining operation. Since both theinner trough and support trough are machined at the same time thelongitudinal opening in each channel is accurately aligned with that inthe other channel. If air gap 6 is to be left between the bottom of theinner trough and the support trough, the inner tube is out to the propershape before it is inserted into the outer tube.

To make a trough suitable for a 6" cast iron pipe casting machine a 4/2" O.D. outer tube having a /2" thick wall was bored out to provide a.045" clearance between it and an inner tube having a 3 /2" OD. and aAs" wall thickness. Before the inner tube was inserted in the outertube, a flat cut Was made on the bottom side of the inner tube leaving ametal thickness of A" at the thinnest spot. The assembly of the innertube and outer tube was formed into a trough by milling a longitudinalopening through both the inner and outer tube. The two tubes were thentack welded together at the mounted end of the trough and the spout endwas formed to the proper shape.

The foregoing description and the accompanying drawings are merelyexplanatory and illustrative of a presently preferred embodiment of theinvention and are not to be construed as limiting. Various changes,which will now suggest themselves to those skilled in the art, may bemade in the structural details of the trough members. Reference istherefore to be had to the appended claims for a definition of thelimits of the invention.

I claim:

1. A pouring trough for a centrifugal pipe casting machine comprising anelongated outer channel having a longitudinal opening and an innersurface which is greater than a semicircle in transverse cross-section,and an elongated inner channel having a longitudinal opening and anouter surface which is greater than a semicircle in traversecross-section, the inner channel being telescoped within the outerchannel with its longitudinal opening aligned with the longitudinalopening in the outer channel, a sliding clearance being provided betweenthe outer surface of the inner channel and the inner surface of theouter channel, whereby each channel is permitted to expandlongitudinally independently of the other, the two channels being weldedtogether adjacent one end thereof, and at the end opposite the weldedconnection, the inner channel extends beyond the outer channel and theextended portion is shaped to give the desired spout configuration.

2. A pouring trough according to claim 1 wherein an insulating air spaceis provided between the inner and outer channels diametricallyoppositethe aligned longitudinal openings.

References Cited by the Examiner UNITED STATES PATENTS 1,465,153 8/1923Allard 2265 1,517,608 12/1924 Atkins 2265 1,584,840 5/1926 Cammen 22651,736,424 11/1929 Bell 2265 1,849,072 3/1932 Clark 22--65 1,881,22810/1932 Pape 2265 2,066,229 12/ 1936 Ridley et al. 2265 2,073,200 3/1937 Dumas 2265 2,853,755 9/1958 Beyer 22200.5 3,004,314 10/1961 Beyer222005 FOREIGN PATENTS 212,931 7/ 1924 Great Britain.

J. SPENCER OVERHOLSER, Primary Examiner.

R. S. ANNEAR, Assistant Examiner.

1. A POURING TROUGH FOR A CENTRIFUGAL PIPE CASTING MACHINE COMPRISING ANELONGAED OUTER CHANNEL HAVING A LONGITUDINAL OPENING AND AN INNERSURFACE WHICH IS GREATER THAN A SEMICIRCLE IN TRANSVERSE CROSS-SECTION,AND AN ELONGATED INNER CHANNEL HAVING A LONGITUDINAL OPENING AND ANOUTER SURFACE WHICH IS GREATER THAN A SEMICIRCLE IN TRAVERSECROSS-SECTION, THE INNER CHANNEL BEING TELESCOPED WITHIN THE OUTERCHANNEL BEING TELEOPENING ALIGNED WITH THE LONGITUDINAL OPENING IN THEOUTER CHANNEL, A SLIDING CLEARANCE BEING PROVIDED BETWEEN